WO2012145193A1 - Oscillateurs à faible bruit - Google Patents

Oscillateurs à faible bruit Download PDF

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Publication number
WO2012145193A1
WO2012145193A1 PCT/US2012/032875 US2012032875W WO2012145193A1 WO 2012145193 A1 WO2012145193 A1 WO 2012145193A1 US 2012032875 W US2012032875 W US 2012032875W WO 2012145193 A1 WO2012145193 A1 WO 2012145193A1
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WO
WIPO (PCT)
Prior art keywords
transistor
coupled
output
electrode
differential amplifier
Prior art date
Application number
PCT/US2012/032875
Other languages
English (en)
Inventor
Roger L. Clark
William W. Cooper
Mark J. Gugliuzza
Benjamin J. ANNINO
Original Assignee
Raytheon Company
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Filing date
Publication date
Application filed by Raytheon Company filed Critical Raytheon Company
Priority to EP12714515.9A priority Critical patent/EP2700157B1/fr
Priority to AU2012245734A priority patent/AU2012245734B2/en
Priority to JP2014506448A priority patent/JP5800985B2/ja
Publication of WO2012145193A1 publication Critical patent/WO2012145193A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1231—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier comprising one or more bipolar transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/02—Details
    • H03B5/04—Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1203—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier being a single transistor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/18—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising distributed inductance and capacitance
    • H03B5/1841—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising distributed inductance and capacitance the frequency-determining element being a strip line resonator
    • H03B5/1847—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising distributed inductance and capacitance the frequency-determining element being a strip line resonator the active element in the amplifier being a semiconductor device
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/20—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator
    • H03B5/24—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator active element in amplifier being semiconductor device
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H03B5/326—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator the resonator being an acoustic wave device, e.g. SAW or BAW device
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
    • H03B5/362—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device the amplifier being a single transistor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
    • H03B5/366—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device and comprising means for varying the frequency by a variable voltage or current
    • H03B5/368—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device and comprising means for varying the frequency by a variable voltage or current the means being voltage variable capacitance diodes

Definitions

  • the present invention relates to RF oscillators and more particularly to RF oscillators having low levels of phase noise.
  • low noise oscillators have a wide range of applications such as in navigation, radars and communication systems.
  • 1/f noise from the transistors may significantly degrade oscillator phase noise.
  • One technique used to produce low noise oscillators is to screen oscillator transistors for devices having low phase noise. This is time consuming, costly and can sometimes lead to unpredictable yields.
  • Obtaining RF transistors with 1/f noise much less than 1 kHz is desired, but is generally considered impractical. More particularly, RF oscillator phase noise is a dominant factor limiting the performance of many systems.
  • a time based related attribute is the short-term stability or Allan variance.
  • phase noise is often described by its spectral properties.
  • phase noise can have a 1/f 1 characteristic, with n being an integer.
  • n generally varies from 0 to 3.
  • D.B. Leeson in the paper entitled “A simple model of feedback oscillator noise spectrum,” Proc. IEEE, vol. 54, pp. 329-330, Feb. 1966, electronic noise within the resonator bandwidth is increased such that 1/f phase noise is converted into 1/f phase noise when the device is embedded into a high Q oscillator circuit.
  • the implication of this conversion is that phase noise within the resonator bandwidth is greatly increased. Obtaining lower phase noise then requires either lower 1/f phase noise transistors or higher Q resonators.
  • the 1/f phase noise of a RF transistor relates to the phase noise at small offset frequencies from the center resonance frequency of the oscillation signal.
  • the 1/f term applies to noise having a 1/f spectral shape when offset from the 1 GHz output.
  • transistor 1/f phase noise is generally attributed to material and surface defects, the precise mechanisms are not well understood.
  • 1/f phase noise can be associated with the actual 1/f voltage noise of the transistor, but the specific mechanisms of conversion are also not well understood.
  • One mechanism that converts 1/f voltage noise to 1/f phase noise in bipolar transistors is modulation of collector-to-base capacitance resulting from 1/f voltage noise between the collector and base control electrodes.
  • a similar mechanism that converts 1/f voltage noise to 1/f phase noise in field effect transistors is modulation of source-to-base capacitance resulting from 1/f noise between the source and gate control electrodes.
  • Obtaining RF transistors having very low 1/f phase noise is quite difficult due to compromises between RF performance and 1/f noise.
  • Modulation of the collector-base capacitance was proposed as a means of converting 1/f voltage noise to 1/f phase noise.
  • the desire is to provide an RF oscillator with very low phase noise, including 1/f phase noise.
  • it is desired to minimize RF power variations with temperature and process variations.
  • an oscillator having: (A) a transistor a transistor for producing an oscillating output signal at an output electrode of the transistor; (B) a bias circuit for producing a bias signal for the transistor, said bias circuit including an amplifier coupled to an output electrode of the transistor; and (C) a circuit coupled between an output of the amplifier and a control electrode of the transistor, for isolating the bias signal provided by the amplifier from the oscillating output signal.
  • an oscillator circuit having a first feedback loop comprising: a resonator circuit having an input coupled to an output electrode of a transistor and an output coupled to a control electrode of the transistor.
  • the oscillator circuit includes a bias control feedback loop, comprising: a differential amplifier; and a reference voltage coupled to a first input of the differential amplifier.
  • a second input of the differential amplifier is coupled to the output electrode of the transistor.
  • An output of the differential amplifier is coupled to a control electrode of the transistor.
  • a second feedback loop is coupled between the output electrode of the transistor and the control electrode of the transistor.
  • the second feedback loop comprises a resistor and a capacitor serially coupled between the output electrode of the transistor and the control electrode of the transistor.
  • RF blocking circuit is serially connected between the output electrode of the transistor and the first input of the differential amplifier and wherein the resistor and the capacitor are serially coupled between at node between the pair of serially connected oscillator frequency blocking circuits and the control electrode of the transistor.
  • an additional pair of matching and blocking circuits is serially coupled between the output electrode of the transistor and the control electrode of the transistor through the resonator circuit.
  • the second feedback loop is phase noise suppression circuit and provides additional output electrode to control electrode feedback, serves to reduce the gain and shift the phase of higher frequency AC signals in the biasing control loop, and reduces fluctuations in the output electrode to control electrode of the transistor that are outside the bandwidth of the differential amplifier bias control loop.
  • the second loop also affects the RF gain in the oscillation loop and also stabilizes the critical collector-to-base bias voltage.
  • an oscillator circuit is provided having: a transistor; a regenerative feedback loop for producing an output oscillation frequency signal at an output electrode of the transistor having undesirable 1/f voltage noise and associated undesirable phase noise; a negative feedback loop coupled between the output electrode and a control electrode of the transistor for suppressing the 1/f voltage noise and the associated
  • phase noise of the oscillator is reduced by actively controlling biasing and low frequency modulation.
  • This invention uses a novel topology to reduce 1/f transistor phase noise and improve oscillator 1/f 1 phase noise, where n in an integer ranging from 0 to 3. The technique is applicable to a broad class of oscillators.
  • FIG. 1 is an oscillator according to an embodiment of the disclosure.
  • FIG. 2 is an oscillator according to an embodiment of the disclosure.
  • the oscillator includes a transistor Ql ; a resonant circuit 12 coupled between an output electrode, here collector electrode, of the transistor Ql and a control electrode, here base electrode, of the transistor Ql ; and a dc bias circuit 14 for the transistor Ql .
  • the dc bias circuit 14 includes: a voltage producing circuit 16; and a differential amplifier 18.
  • the differential amplifier 18 has: a first input (inverting (-) input) coupled to a fixed reference voltage; a second input (non- inverting (+)) coupled to the voltage producing circuit 16, such voltage producing circuit producing a voltage at the second input (non-inverting (+)) of the difference amplifier 18 related to current Ic passing through the output electrode (collector) of the transistor Ql ; and an output 20 coupled to the control electrode (base) of the transistor Ql .
  • a voltage source VI has: one potential (+) coupled to one terminal of 22 the voltage producing circuit 14; and a second potential (-) coupled to a second terminal 24 of the voltage producing circuit 14.
  • a third terminal 26 of the voltage producing circuit 14 is coupled to the second input (non-inverting (+)) of the differential amplifier 18.
  • the voltage producing circuit 14 includes a first resistor R4 coupled between the first potential and the second input of the differential amplifier (non-inverting (+)) and a second resistor R5 between an additional electrode (emitter) of the transistor Ql and the second potential (i.e., terminal 24).
  • An inductor LI is coupled between the second input (non-inverting (+)) of the differential amplifier 18 and the output electrode (collector) of the transistor Ql .
  • a capacitor C3 is coupled between the first input (inverting (-)) of the differential amplifier 18 and the output 20 of the differential amplifier 18.
  • a third resistor R3 and a fourth resistor R6 are connected together at a node 30, such node 30 being coupled to the second potential (i.e., terminal 24) through a capacitor C4, the third resistor R3 being coupled between the output 20 of the differential amplifier 18 and the node 30 and the fourth resistor R6 being coupled between the node 30 and the control electrode (base electrode) of the transistor Ql .
  • the fixed voltage is a voltage produced at node 32 by a resistor divider 34 made up of resisters Rl and R2 coupled between the first and second potentials of the supply VI .
  • the transistor Ql is the oscillator transistor.
  • the differential amplifier 18 is chosen to have low 1/f voltage noise properties.
  • a resistor R7 is the RF load resistor with typical value of 50 ohms.
  • Inductor LI is used for RF isolation and may also take the form of a distributed transmission line.
  • Capacitor CI is a bypass capacitor having very low reactance at the oscillation frequency.
  • the two port device is the resonant feedback circuit 12 and could be a lumped element LC, an acoustic resonator such as SAW, or a distributed resonator such as a transmission line or a dielectric resonator.
  • the two-port could include a means of tuning the oscillator frequency such as a varactor diode.
  • Transistor Ql is shown as a bipolar device, but may also be a FET; in which case the control electrode is the gate electrode and the collector and emitter electrodes are source and drain electrodes.
  • the semiconductor material may be silicon, GaAs, GaN or other semiconductor materials. Biasing is provided by using as the differential amplifier 18 a differential amplifier having low 1/f voltage noise. For example, commercially available differential amplifiers are available with a typical 1/f voltage noise intercept of less than 10 Hz.
  • a reference voltage formed by the voltage divider of Rl and R2 and also having low 1/f voltage noise is used as the inverting input, and a voltage proportional to collector current of the RF transistor is used as the non-inverting input.
  • the feedback path from the voltage at the R4- Ll node is applied to the positive differential amp input due to the 180 phase shift of transistor Ql at low frequencies. Effectively the amplifier 19 positive input (non-inverting input (+)) becomes a negative feedback path, and the reference voltage at node 32 is applied to what is commonly used as the negative input to the op-amp.
  • the output 20 from the differential amplifier 18 is used to provide a voltage for biasing the input (here emitter) to the RF transistor Ql .
  • Resistor R3, R6 and capacitor C4 serve to isolate the RF signal from the biasing function and also suppress phase noise.
  • An additional capacitor C3 serves as a phase shift component to establish adequate phase margin and ensure that noise processes are not regenerated by the very high differential voltage gain.
  • the biasing configuration ensures that the voltage of the non-inverting input (+) of the differential amplifier 18 will be essentially equal to the voltage of the inverting input (-). Since the noise at the inverting input (-) is derived from a reference voltage at node 32 with very low noise, the noise at the non-inverting input (+) will also be similarly quiet.
  • the biasing circuitry extends down to DC, the oscillator frequency is also stabilized with respect to variation in temperature and parametric variations of the RF transistor.
  • the circuit can be implemented from discrete devices or as an integrated circuit.
  • an oscillator 10' here producing an RF oscillating output signal, is shown having an output transistor arrangement QA' (here made up of a pair of transistors Q1A' and Q2 having base electrodes connected together, and collector electrodes connected together at node A; the emitter electrode of transistor Ql A' being connected to ground through a resistor R6A' and the emitter electrode of transistor Q2A' being connected to ground though resistor R6B', as shown.
  • output transistor arrangement QA' here made up of a pair of transistors Q1A' and Q2 having base electrodes connected together, and collector electrodes connected together at node A; the emitter electrode of transistor Ql A' being connected to ground through a resistor R6A' and the emitter electrode of transistor Q2A' being connected to ground though resistor R6B', as shown.
  • a DC bias control loop 1 having a differential amplifier 18' fed by a reference voltage produced by a voltage divider (made up of resistors Rl' and R2', serially connected between a supply voltage, +V, and ground, as shown) at node B and fed to the inverting (+) input of the differential amplifier 18' and a voltage produced at the collector electrodes of transistors Ql A' and Q2A' and fed to the non-inverting (-) input of the differential amplifier 18' through serially connected impedance matching and RF blocking elements, here, for example, inductors LI ' and L2', respectively, as shown.
  • the differential amplifier 18' is selected to have low 1/f voltage noise properties.
  • a resistor R9' and a shunt capacitor C3' Disposed between node B and the output of the differential amplifier 18' are a resistor R9' and a shunt capacitor C3', as shown.
  • the output of the differential amplifier 18' is fed to the base electrodes of the pair of transistors Ql A' and Q2 through a pair of serially connected resistors R3' and R5', as shown, to complete the DC bias control loop 11 '.
  • the resistors R3' and R5' are connected together at a node C; such node C; being connected: to ground through a resistor R8'; and the output of a resonator circuit 12' through resistor R7'.
  • a resistors R4' and capacitor CI' are connected together at node D and are serially connected between the voltage supply, + V, and ground.
  • the oscillator frequency feedback loop 17' includes: power splitter 15' fed by the output (collector electrodes) of the pair of transistors Q1A and Q2A'; a pair of serially inductors L3' and L4' (and capacitor C4' connected between ground and a node E connected to the pair of inductors L3' and L4' as shown); the resonator circuit 12' having an input coupled to the output of the pair of transistors Ql A' and Q2A' (the collector electrodes of the pair of transistors Q1A' and Q2A'); and the resistor R7' connecting the output of the resonator circuit 12' to the base electrodes of the pair of transistors Q1A' and Q2A' through capacitor C5', to complete the oscillator frequency feedback loop 17'.
  • a second output of the power splitter 15' provides the output of the oscillator 10', as indicated.
  • the pair of serially inductors L3' and L4 1 and capacitor C4' provide the proper positive (regenerative) phase shift for the feedback loop 17'.
  • the pair of transistors Ql A' and Q2A' provide RF gain and resistors R6A' and R6B' provide some emitter feedback and gain stabilization.
  • the resistors R7' and R8' reduce the RF power level slightly but also control the impedance presented to the control electrode (base) of Q1A' and Q2A'.
  • Resonator 12' may have an impedance not ideal for low phase noise signal generation away from the resonator frequency and resistors R7' and R8' control this impedance.
  • the RF blocking structure here inductor LI', is used for RF isolation from the voltage source +V and from the non-inverting input of the differential amplifier 18' and may also take the form of a distributed transmission line.
  • Capacitor CI' is a bypass capacitor having very low reactance at the oscillation RF frequency to thereby direct any RF energy to ground.
  • the resonator circuit 12' is a two port and may be, for example, a lumped element LC, an acoustic resonator such as SAW, or a distributed resonator such as a transmission line or a dielectric resonator.
  • the two-port may, for example, include a means of tuning the oscillator frequency such as a varactor diode.
  • the differential amplifier 18' is used to bias and stabilize the oscillator transistors Q1A' and Q1B.' Alternatively, transistor Q1 B' and resistor R6B' may be eliminated to produce a simpler, but lower cost oscillator.
  • Transistors Q1A' and Q1B' are referred to as Ql' herein.
  • Resistors R6A' and R6B' are referred to as R6' herein.
  • Transistor Ql' is shown as a bipolar device, but may also be a FET.
  • the semiconductor material may be silicon, GaAs, GaN or other semiconductor materials.
  • the power splitter 15' directs a portion of the RF power to the RF output and a portion of the RF power into inductor L3'.
  • the power splitter 15' is of any well-known power splitter, here for example Mini Circuits, Brooklyn, NY, model HPQ-05.
  • Inductors L3', capacitor C4' and inductor L4' shift the phase of the RF power into the resonator 12'.
  • the resonator 12' is a high Q two port device such as a crystal, SAW, cavity or MEMS resonator and may include means of tuning the resonator such as with varactor diodes.
  • Resistors R7' and R8' reduce the RF power into the base electrode of transistor Ql' such that the overall gain through loop 17' is approximately 3 dB.
  • resistors R7' and R8' stabilize the impedance presented to the base control electrode of transistor Ql' at frequencies which are offset from the peak amplitude of the resonator, but still of interest in the overall phase noise spectrum of the oscillator 10'.
  • Biasing is provided by using as the differential amplifier 18'; a differential amplifier having low 1/f voltage noise.
  • a differential amplifier having low 1/f voltage noise For example, commercially available differential amplifiers such as the OP27 manufactured by Analog Devices, Norwood, MA, are available with a typical 1/f voltage noise intercept of less than 10 Hz.
  • a reference voltage formed by the voltage divider of Rl ' and R2' at node B and also having low 1/f voltage noise is used as the inverting input of the differential amplifier 18', and a voltage proportional to collector current of the RF transistor Ql ' is used as the non- inverting input.
  • the feedback path 1 ⁇ from the voltage at the R4'-L1 ' node is applied to the positive differential amplifier 18' input due to the 180 phase shift of transistor Ql' at low frequencies. Effectively the amplifier 18' non-inverting (positive) input becomes a negative feedback path 1 ⁇ , and the reference voltage at node B is applied to what is commonly used as the inverting (negative) input to the operational amplifier 18'.
  • the output from the differential amplifier 18' is used to provide a voltage for biasing the input to the RF transistor Ql '
  • Resistor R3' serves to isolate the RF signal from the DC biasing function.
  • Resistor R5' allows the control signal for Ql ' to be applied to the base electrode of transistor Ql '.
  • the feedback loop 17' which is a positive, regenerative feedback loop that produces the desired oscillation frequency signal, here the RF output signal of the oscillator 10'; however, this loop 17' includes undesirable voltage noise and associated unwanted phase noise at the collector electrode of transistor Ql '; and, (2) The negative, degenerative feedback loop 1 1 ' for unwanted suppressing 1/f voltage noise and associated unwanted phase noise in the collector of transistor Ql '.
  • the transistor Ql ' collector and base control electrodes are shared in both feedback loops 1 and 17'.
  • the output of the differential amplifier 18' provides enough DC voltage at the base control electrode of transistor Ql ' so that the voltage at node D will be nearly identical to the voltage at node B.
  • Feedback loop 1 1 ' will generate a current in the collector of transistor Ql ' that is equal in magnitude but opposite in phase to the inherent collector noise current of transistor Ql '. This noise is translated to the base control electrode of transistor Ql ' by the feedback loop I V. Low frequency noise at the collector of transistor Ql ' is suppressed by the action of feedback loop 1 ⁇ .
  • Transistor Ql' can have voltage gain from the base control electrode to the collector electrode. This voltage gain will be approximately R4'/(l/gm + R6'), where gm is the transistor Ql' transconductance.
  • feedback loop 1 controls the voltage at node D and thereby the collector voltage of transistor Ql' for low frequencies
  • the signal generated by feedback loop 1 1 ' at the base control electrode of transistor Ql ' will be reduced by the ratio of the low frequency gain of Ql'.
  • the collector electrode voltage noise is now suppressed, and the base electrode voltage noise is also reduced by the low frequency voltage gain of Ql', the total collector-to-base voltage noise will be reduced by feedback loop 11 '.
  • the noise reduction extends down to DC and includes the critical region where 1/f voltage noise would otherwise be significant. Since phase noise of a transistor is known to be affected by collector-to-base voltage noise, the low frequency phase noise of Ql' is now reduced by feedback loop 1 ⁇ , including 1/f phase noise.
  • phase margin is required in the DC bias loop 1 ⁇ , such as 60 degrees or more. Phase margin less than 60 degrees will result in amplification of phase noise, producing increased phase noise in the region with lower phase margin. Lower phase margin results in elevated regions of phase noise in the phase noise floor of the RF oscillation signal.
  • an additional oscillator frequency negative feedback loop 15' is provided to suppress the phase noise at the collector electrode of transistor Ql'.
  • the additional oscillator frequency feedback loop 15' is a phase noise suppression circuit and includes the resistor R5' and capacitor C2' and resistor R10'. This additional loop 15' serves to suppress phase noise in the RF loop 17' via reduced voltage noise in the collector- to-base noise voltage of transistor Ql'.
  • Capacitor C2' and resistor R10' are serially connected between node F and node C. At the intermediate frequencies resistor R10' and capacitor C2' have a low impedance and are have a shared path with feedback loop 11 ' . Resistor R10' and capacitor C2' reduce the gain of feedback loop 1 1 ' by the amount that otherwise be generated by transistor Ql '. Resistor Rl 0' and capacitor C2' act as a high pass filter, shunting, via path 19'; a portion of the control signal of feedback loop 11 1 around transistor Ql ' at the above-mentioned intermediate frequencies (i.e., away from the loop 1 1 ', and hence away from the control electrode, directly to the collector electrode).
  • Resistor R5' along with the capacitor C2', additionally provides collector-base RF feedback from the junction (node F) of inductors LI' and L2' at the collector electrode of transistor Ql' to the base electrode of transistor Ql'.
  • the additional phase noise suppression circuit feedback loop 15' is from the collector electrode of transistor Ql', through the inductor L2', through resistor RIO', capacitor C2', through resistor R5', and back to the collector electrode of transistor Ql', as shown.
  • the feedback is a negative feedback because of the 180 degree phase shift between the base and collector of transistor Ql'.
  • Capacitor C2' is selected to be an RF bypass capacitor and serves to reduce the gain and shift the phase of intermediate frequency signals in the biasing control loop.
  • capacitor C2' reduces collector electrode to base electrode voltage noise of transistor Ql' that are outside the bandwidth of the differential amplifier 18' DC bias control loop 11 '.
  • the DC biasing configuration ensures that the voltage of the non-inverting input of the differential amplifier 18' will be essentially equal to the voltage of the inverting input of such differential amplifier 18'. Since the 1/f voltage noise at the inverting input is derived from a reference voltage at node B with very low 1/f voltage noise, the 1/f voltage noise at the non-inverting input will also be similarly quiet.
  • Capacitor C2' is selected to be an RF bypass capacitor preventing DC from passing through the additional oscillator frequency feedback loop 15.
  • Resistors R5' and R10' provide RF feedback from the collector electrode back to the control electrode of transistor Ql' and are selected to provide approximately 3 dB of gain around the RF frequency feedback loop 17'.
  • capacitor C2', R5' and R10' influence the effects of the DC biasing control by affecting the gain and phase margin of the DC biasing loop 1 1 '. While computer analysis of the low frequency loop gain and phase characteristics provide insight into proper values, non-linear effects also influence the circuit behavior.
  • capacitors C2', R5' and R10' influence the phase noise floor of the RF oscillation signal.
  • the phase noise floor is the region of frequencies offset from the RF oscillation frequency which is outside of the three dB bandwidth of the resonator circuit 12'.
  • the additional phase noise suppression circuit feedback loop 15' provides additional phase margin in the DC bias control loop 11 1 to improve phase noise in Ql' at the intermediate frequencies.
  • the additional phase noise suppression circuit feedback loop 15' also serves to stabilize the collector-to-base voltage of Ql ' resulting in further suppression of the phase noise of Ql '. Absent the additional phase noise suppression circuit feedback loop 15', phase noise of transistor Ql ' would increase dramatically at the intermediate frequencies.
  • the circuit 10' can be implemented from discrete devices or as an integrated circuit.
  • the oscillator circuit 10' includes a regenerative feedback loop 17' for producing an output oscillation frequency signal at an output electrode of the transistor Ql' having undesirable 1/f voltage noise and associated undesirable phase noise.
  • a negative feedback loop 11 ' is coupled between the output electrode and a control electrode of the transistor Ql' for suppressing the 1/f voltage noise and the associated undesirable phase noise at the output electrode.
  • a circuit having capacitor C2' and R10' and R5' is coupled between the output electrode and the control electrode for provide the feedback loop 15' to the oscillation frequencies to stabilize operation of the transistor Ql' and includes a path 19', having the capacitor C2' and R10', for coupling intermediate frequencies in the negative feedback loop 11 ' away from the control electrode to the output electrode of the transistor Ql'.
  • This circuit having resistors R3' R5 1 , R10' and capacitor C2' suppress phase noise in the oscillator.
  • An exemplary set of values for elements in oscillator circuit 10', here for producing an oscillator frequency of the output of the power splitter 15' of approximately 450 MHz are:
  • +V is 10 volts
  • R2' 845 ohms
  • an oscillator includes (A) a transistor for producing an oscillating output signal at an output electrode of the transistor; (B) a bias circuit for producing a bias signal for the transistor, said bias circuit including an amplifier coupled to an output electrode of the transistor; and (C) a circuit coupled between an output of the amplifier and a control electrode of the transistor, for isolating the bias signal provided by the amplifier from the oscillating output signal.
  • the oscillator may also include the following feature wherein the bias circuit comprises: (a) the amplifier comprises: (i) an input coupled to the output electrode; and (ii) an output coupled to the control electrode for providing the bias signal at the control electrode.
  • a transistor for producing an oscillating output signal at an output electrode of the transistor alternatively includes (A) a transistor for producing an oscillating output signal at an output electrode of the transistor; (B) a resonant circuit coupled between the output electrode of the transistor and a control electrode of the transistor; (C) a dc bias circuit for producing a bias signal at the control electrode of the transistor, such bias circuit comprising: (i) a voltage producing circuit; (ii) a differential amplifier having: (a) a first input coupled to a first reference voltage; (b) a second input coupled to the voltage producing circuit, such voltage producing circuit producing a voltage at the second input of the difference amplifier related to current passing through the electrode of the transistor; and (c) an output for providing the bias signal; wherein the voltage producing circuit includes a first resistor coupled between the first reference voltage and the second input of the differential amplifier; (d) an inductor coupled between the second input of the differential amplifier and the output electrode of the transistor; and (e) a capacitor coupled between the first input of the differential amplifier
  • an oscillator alternatively includes (A) a transistor; (B) a resonant circuit coupled between an output electrode of the transistor and a control electrode of the transistor; (C) a dc bias circuit for producing a bias signal for the transistor, such bias circuit comprising: (i) a voltage producing circuit; (ii) a differential amplifier having: (a) a first input; (b) a second input coupled to the voltage producing circuit, such voltage producing circuit producing a voltage at the second input of the difference amplifier related to current passing through the output electrode of the transistor; (c) an output for providing the bias signal; (D) a circuit, comprising: (a) a first resistor; (b) a second resistor connected to the first resistor at a node; (c) wherein the first resistor is coupled between the output of the differential amplifier and the node; (d) wherein the second resistor is coupled between the node and the control electrode of the transistor; and (e) a capacitor coupled between the node
  • the oscillator may also include one or more of the following features: a second capacitor coupled between the node and the first input of the differential amplifier; a voltage source having: one potential coupled to one terminal of the voltage producing circuit; and wherein the reference potential is a second potential of the voltage source; a voltage source having: one potential coupled to one terminal of the voltage producing circuit; and wherein the reference potential is a second potential of the voltage source.
  • an oscillator alternatively includes a transistor; a first feedback loop comprising: a resonator circuit having an input coupled to an output electrode of the transistor and an output coupled to a control electrode of the transistor; a bias control feedback loop, comprising: a differential amplifier; a reference voltage coupled to a first input of the differential amplifier; wherein a second input of the differential amplifier is coupled to the output electrode of the transistor; and wherein an output of the differential amplifier is coupled to a control electrode of the transistor; and a second feedback loop coupled between the output electrode of the transistor and the control electrode of the transistor.
  • the oscillator may also include one or more of the following features: wherein the second feedback loop comprises a resistor and a capacitor serially coupled between the output electrode of the transistor and the control electrode of the transistor; an oscillator frequency blocking circuit pair of inductors serially connected between the output electrode of the transistor and the first input of the differential amplifier and the control electrode of the transistor; an additional pair of oscillator frequency blocking circuits serially coupled between the output electrode of the transistor and the control electrode of the transistor through the resonator circuit; wherein the output of the differential amplifier is coupled to the control electrode of the transistor through a first resistor and a serially connected second resistor connected, the first and second resistors being connected at a node, and wherein the second feedback loop is connected between the node and the output electrode of the transistor; wherein the second feedback loop includes a capacitor coupled between the node and the output electrode of the transistor; wherein second feedback loop includes an oscillator frequency blocking circuits coupled the capacitor and the output electrode of the transistor; a capacitor and pair of oscillator frequency blocking circuits serial
  • the oscillator may also include a resistor and a capacitor serially coupled between the negative feedback loop and the output electrode of the transistor.
  • an oscillator alternatively includes a transistor; a resonator circuit having an input coupled to an output electrode of the transistor and an output coupled to a control electrode of the transistor; a bias control feedback loop, comprising: a differential amplifier; a reference voltage coupled to a first input of the differential amplifier; wherein a second input of the differential amplifier is coupled to the output electrode of the transistor; and a circuit coupled to the output of the differential amplifier, comprising: a first resistor coupled between the output of the differential amplifier and the control electrode of the transistor; a second resistor; a capacitor serially coupled to the second resistor; wherein the second resistor and serially coupled capacitor are serially connected between the output of the differential amplifier and the output electrode of the transistor.
  • an oscillator alternatively includes a transistor; a resonator circuit having an input coupled to an output electrode of the transistor and an output coupled to a control electrode of the transistor; a bias control feedback loop, comprising: a differential amplifier; a reference voltage coupled to a first input of the differential amplifier; wherein a second input of the differential amplifier is coupled to the output electrode of the transistor; and a circuit coupled to the output of the differential amplifier, comprising: a resistor coupled between the output of the differential amplifier and the control electrode of the transistor; a capacitor; wherein the capacitor is connected between the output of the differential amplifier and the output electrode of the transistor.
  • the oscillator may also include one or more of the following features: wherein the circuit includes a including a second resistor serially coupled to the first-mentioned resistor at a node and wherein the capacitor is coupled between the node and the output electrode; including a third resistor serially coupled to the capacitor and wherein the capacitor and third resistor are serially coupled between the node and the output electrode.

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  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)

Abstract

L'invention concerne un oscillateur ayant : (A) un transistor servant à produire un signal de sortie oscillant à une électrode de sortie du transistor ; (B) un circuit de polarisation servant à produire un signal de polarisation pour le transistor, ledit circuit de polarisation comprenant un amplificateur couplé à l'électrode de sortie du transistor ; et (C) un circuit couplé entre une sortie de l'amplificateur et une électrode de commande du transistor, servant à isoler le signal de polarisation produit par l'amplificateur à partir du signal oscillant ; et (D) un circuit résonateur ayant une entrée couplée à une électrode de sortie du transistor et une sortie couplée à une électrode de commande du transistor.
PCT/US2012/032875 2011-04-18 2012-04-10 Oscillateurs à faible bruit WO2012145193A1 (fr)

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EP12714515.9A EP2700157B1 (fr) 2011-04-18 2012-04-10 Oscillateurs à faible bruit
AU2012245734A AU2012245734B2 (en) 2011-04-18 2012-04-10 Low noise oscillators
JP2014506448A JP5800985B2 (ja) 2011-04-18 2012-04-10 低ノイズ発振器

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US13/088,733 2011-04-18
US13/088,733 US8451071B2 (en) 2008-11-24 2011-04-18 Low noise oscillators

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WO2015179407A1 (fr) 2014-05-19 2015-11-26 The Regents Of The University Of California Émetteur-récepteur à réaction à base de mems
EP3010150A1 (fr) * 2014-10-16 2016-04-20 Stichting IMEC Nederland Dispositif d'oscillateur
EP3373449B1 (fr) * 2017-03-10 2020-10-07 EM Microelectronic-Marin SA Oscillateur électronique
US10483913B2 (en) * 2017-07-13 2019-11-19 Qualcomm Incorporated Low power crystal oscillator
US10840853B2 (en) * 2019-02-26 2020-11-17 Keysight Technologies, Inc. Low phase noise oscillator using negative feedback
JPWO2020245693A1 (fr) * 2019-06-07 2020-12-10
EP4020798A1 (fr) 2020-12-23 2022-06-29 Carrier Corporation Circuit oscillateur avec un résonateur à guide d´ondes intégré en surface
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EP2700157A1 (fr) 2014-02-26
US20110193641A1 (en) 2011-08-11
US8451071B2 (en) 2013-05-28
TWI523411B (zh) 2016-02-21
AU2012245734B2 (en) 2015-02-19
TW201310892A (zh) 2013-03-01
JP5800985B2 (ja) 2015-10-28
JP2014512155A (ja) 2014-05-19
AU2012245734A1 (en) 2013-10-17
EP2700157B1 (fr) 2016-10-26

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